Cook macaroni according to package directions, except omit any oil or salt. Drain; set aside. In large bowl combine yogurt, cucumber, carrot, mayonnaise dressing, dill, salt, and pepper. Add cooked pasta and salmon; toss gently to coat. Cover; refrigerate for at least 4 hours or up to 24 hours.
Meanwhile, for tomato stars, cut out 1/2 inch of the core from each tomato. Invert tomatoes. For each tomato, cut from the top to, but not quite through the stem end to make 6 wedges.
To serve, place tomatoes on plates. Spread wedges slightly apart; fill with salmon-pasta mixture. Makes 4 servings.